The present invention relates to an improved remote control unit, and more particularly relates to improvement in the zero-point resetting function of a remote control unit advantageously usable for automatic steering system of small-sized boats and cruisers.
In general, a remote control unit is provided with a variable resistor whose resistance is freely adjustable by manually turning a dial mechanically coupled to the variable resistor. In use, the remote control unit is operationally coupled to a rudder mechanism via a main control unit. Change in the resistance of the above-described variable resistor causes corresponding change in the electric signal, e.g. voltage signal, to be passed to the main control unit from the remote control unit in order to activate the rudder mechanism.
The conventional remote control unit of the above-described type is a simple combination of a manually operable dial with a potentiometer and is provided with the no automatic zero-point resetting function. Therefore, when the dial is turned over a prescribed angle and, as a result, the boat starts to change the sailing course to the selected one, the dial needs to be gradually and carefully returned to the zero-point in accordance with development of the change in the sailing course. This manual resetting operation required highly skilled technique based upon long experience in practice. In addition, such gradual zero-point resetting adjustment is quite troublesome and inconvenient for the operator who is busy with various work necessary for safe navigation of the boat. Further, when any shock is applied to the remote control unit and the dial is made to turn unexpectedly, the rudder is turned over an angle corresponding to the unexpected turning angle of the dial and kept at the turned angular position until the operator finds the unexpected turning of the dial and resets the dial to the zero-point. This naturally causes corresponding unexpected change in the sailing course of the boat which is seriously dangerous when the boat sails, for example, through a narrow strait.